Dinosaurs When dinosaur bones were first found they thought that they belonged to giant lizards. The word "dinosaur" means "terrible lizard". The larger dinosaurs must have seemed to be terrible to the smaller animals. Some of the first dinosaurs were only about as big as a small dog. That is how big the horses of that time were. Over the years, as the dinosaurs aged, they grew to be much more large in size. The sizes of dinosaurs ranged greatly, all the way from two feet long to one hundred and fifty feet long. They weighed as much as fifty tons, which is seven African Bull Elephants.We first discovered